Among experts skilled in the art, analytical devices are known for the automatic determination of clinical chemical as well as immunodiagnostic parameters. The devices for determining clinical chemical parameters must meet different requirements than devices for determining immunological parameters.
Clinical chemical parameters are typically determined in the liquid phase of a sample. At least one reagent is added to the sample that causes a change in optical density. Then the sample is placed in a measuring cell that is horizontally irradiated by an optical sample beam. The reaction temperature normally is 37° C. (=body temperature). The reaction devices must be made of properly resistant material to withstand the often aggressive reagents.
Immunodiagnostic parameters however are determined based on the ELISA principle using a substance coupled to a solid phase.
The reaction temperature typically is room temperature, i.e. 18° C. to 25° C. Preparation and storage of the antigen- or antibody-coupled solid phase is particularly critical for these tests. It is especially important to optimally bind the antigens or antibodies to the solid phase.
EP 1 255 115 A2 therefore proposes an analytical insert for one-time use when performing an ELISA in a fully automated analytical device. The insert is a single-piece molded plastic part comprising multiple cavities. The first cavity accommodates the sample, the other cavities contain reagents for performing the ELISA. The housing also comprises two recesses that are interconnected by a slit. Two interconnected wells that were broken out of a microtiter plate coated with the respective antigen or antibody can be inserted into these recesses.
This solution, however, has several disadvantages. For example, the user has to insert the respective wells into the analytical insert, which is more or less well working depending on the architecture of the recess. There is a risk that the reagents in the other cavities may spill out of the cavities when the user has to apply an adequate compressive force to press the well safely into the analytical insert. There is another risk that the well in the end may not be correctly positioned in the analytical device, which may result in undesirable light refraction and deflection of the sample beam of the photometric device and falsify the analysis. In addition, the analytical insert is very fragile, and just the removal of the safety film from the reagent-filled cavities may bend the insert enough so that it can no longer be inserted into the analytical device.
Another disadvantage is that the analytical insert can only be used in devices for performing immunodiagnostic analyses. If it is desirable to determine clinical chemical parameters at the same time, the user has to insert another completely differently composed sample into another device. This can hardly be done in smaller doctor's offices, since it requires the purchase of one expensive device for analyzing immunodiagnostic values and the purchase of a second expensive device for analyzing clinical chemical parameters.
It is therefore the problem of the invention to overcome these and other disadvantages of prior art and to provide a reagent cartridge that can be produced in an easy and cost-efficient way and is particularly easy to handle by the user. The reagent cartridge shall also be suitable for determining immunodiagnostic and clinical chemical parameters in one and the same sample.